# Tag Info

### Do I need a pressure relief/safety valve if my pump can't exceed the rated system pressure?

Not a plumbing engineer, but: What about thermal expansion? You reach a dead end, pump stops. Pumps often have a checkvalve that prevents backflow, so you have now created a pressurized container. ...
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Accepted

### How does this water canon function?

On the backside I can see a valve assembly, I don't see enough detail but it's likely a connector for compressed air. Assuming that the mechanism is simple, compress the air in the square part then ...
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### Do I need a pressure relief/safety valve if my pump can't exceed the rated system pressure?

Certainly not all piping systems need relief valves. The specifics of the application matter. Relief valves typically protect vessels that can store significant energy and release it violently at ...
• 6,969

### How are springs that are designed for 100% extension different for ones that are designed for 60% extension?

For a given free length and spring rate there are an infinite number of designs of coil spring. However, there are many practical limitations that limit the options. A spring with a few coils, of thin ...
• 737

### I am looking to make thread changes to a handpiece for laser hair removal equipment

Looking at a the bottle cap of a 1/2 gallon plastic (blow molded) milk jug, for inspiration. Is skinny, and happens to have a triple-start thread like yours. So maybe the triple-start thread is a good ...
• 1,561

### Is rain like bullets at supersonic speed?

Let's try .034 g, 343 m/s: I get 2 joules. .22 long rifle KE = ~ 135 J. So no, it isn't even close. The key here is to verify the assumptions in your calculations.
• 6,969
Accepted

### Would a conical-shaped solenoid be propelled by its interaction with the Earth's magnetic field?

I think you'll be very disappointed. Figure 1. Image source: Science Class. Your coil will form a very weak magnet since it has an air core. (A good solenoid will use an iron core as it has a ...
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### Braking system for a miniature ‘Drop tower’ rollercoaster

Well, if you must use magnets then its possible to utilize a neat physics trick. See there are materials that are paramagnetic (aluminium, copper etc). A magnetic field moving through a paramagnetic ...
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### What's the best way to mount many clock hands on a custom clock?

The question is vague enough as to be at risk for closing, but I'll toss one suggestion your way. If you look at a conventional clock assembly, you'll note that the (usually metal) hands have a ...
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### How are springs that are designed for 100% extension different for ones that are designed for 60% extension?

The ratio of the spring diameter to the wire diameter is the primary factor.
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### I am looking to make thread changes to a handpiece for laser hair removal equipment

People cross threading joints is usually due to alignment, consider a sleeve to control alignment then engage the thread. Check out the types of joint used in pool cues - uniloc etc that cannot be ...
• 15.9k
1 vote

### Is there any elemental pieces template (blank) which together forms a corrugated box of desired size, or is there anything similar to it?

If I had to spec elementary pieces of a box: There are faces. They are made of some thickness of cardboard and they are flat. There are bends. These are not flat and through the process of folding ...
• 1,352
1 vote

### Electronic enclosure - Long screw holes

Short screws can be used to hold thick pieces together in the following way: we redesign the half of the box through which the fastening screws will be driven by replacing the simple clearance hole ...
1 vote

### Electronic enclosure - Long screw holes

Another option would be have counterbore holes on the bottom half so that you can use a "normal" screw. if necessary, you could look at blanking the holes on the bottom half with some sort ...
• 1,841
1 vote

### Electronic enclosure - Long screw holes

So, one option is to make bulges on the sides and end to have the screws - a technique used on many items from plastic boxes to engines.
• 15.9k
1 vote

### Can this new AC motor/generator design work?

I'm not great with the theory of electromagnetism but the one principle that I do understand is that air gaps are the application killer. Have a look at any electromagnetic circuit and you will see ...
• 10.9k
1 vote

### Could someone help me with this physics problem about water pressure

Real Pillow Tank Typical soft-sided uncontained pillow tanks have a $\lesssim 1$ psi pressure relief valve (PRV) at the centre of the top, which is the highest point when the tank is filled. (See, for ...
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1 vote

### How are springs that are designed for 100% extension different for ones that are designed for 60% extension?

Let's compare two springs of the same alloy but with different numbers of turns $N_1 =2 N_2$ . over the length of the coil, $L$ Now if we extend the coils to a length $$L=2L_{inital}$$ The coils with ...
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1 vote

### Braking system for a miniature ‘Drop tower’ rollercoaster

Designing the lifting system isn’t the problem but slowing down the gondola is posing a slight problem, See if you can use the lifting system itself as the braking system. I have looked into using ...
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1 vote
Accepted

### What would be the best capacitor to use for a railgun that uses a capacitor as the projectile?

There are new-technology capacitors available now that can store large amounts of energy; they are called ultracapacitors and have capacities of order ~farads. Before you go out to buy some, however, ...
1 vote

### Do I need a pressure relief/safety valve if my pump can't exceed the rated system pressure?

Another factor to consider--hammer. The valve closes while there's substantial flow, the pressure is going to spike above what the pump can produce. And just because the pump has a max output ...
1 vote

### What are the external bars for on bank vaults?

The big locking pins that those doors have must be aligned precisely with the holes in which they fit, so the pins can be slid into the holes. Precise alignment is accomplished by mechanically pulling ...
1 vote

### Planar linkage design based on output curve?

This is the classic point path linkage synthesis problem. Any kinematics textbook covers this topic. Design of Machinery - Robert Norton, Theory of Machines and Mechanisms - Uicker and Pennock, ...
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